This is one highly profitable blog niche. Trading in Forex and Crypto coins can be insanely profitable, but it is also associated with high risk. As a guide for investors, you can blog about the basics of forex and crypto trading, trading tips, risk management ideas, how to avoid common mistakes etc.
Also include knowledgebase resources on how economic indicators and political events impact in forex and coin trading. You can also offer paid courses on analysis and trading etc. This is a high-paying niche for advertisements as well.
Suggested blog name: ForexCoinsTrade.com